A. Field of the Invention
The present invention is related to RFID tag enclosing structures for protecting RFID tags from hostile industrial environments and more particularly to a RFID tag enclosing structure comprised of a ceramic fiber hardened on a resin having an external bell shaped cover made of vulcanized rubber
B. Description of the Related Art
In the industry, there are several productive processes in which the machinery, materials, tools, etc. need to be identified by RFID tags. One example of such application is in the automotive industry in which the basic vehicle chassises are identified with a RFID tag containing assembling data such as painting color, parts and accessories that comprise the vehicle, etc., so that when the vehicle is assembled in an automated production line, several RFID readers read said identification and the vehicle is automatically assembled in accordance with said information. As expected, the RFID chip must withstand hostile industrial environments, and in order to protect the chip from said environments, it is typically protected by an enclosing structure which is typically comprised by an internal dielectric gel layer covering the RFID chip and battery contained on a plastic cylinder which is surrounded by clay and glass fiber paper and is separated from the antenna at a distance of approximately 1″.
One of the most severe environments of the vehicle assembling process is the painting stage, at which the vehicle being assembled is submitted to shocks, several baths of acid and several layers of paint are applied and treated at high temperatures in drying kilns.
When the actual tag enclosing structure is exposed at such severe environments (heat, vibrations, shocks, contact with acids and solvents), the glass fiber paper breaks, letting the corrosive substances to enter into the plastic cylinder and damage the RFID chip.
In view of the above referred problem, applicant developed a RFID tag enclosing structure comprised of a ceramic fiber hardened on a resin having an external bell shaped cover made of vulcanized rubber, which is specially designed to withstand temperatures of up to 200° C. during a maximum time of 90 minutes, a maximum operational temperature (when read) of 130° C., water submersions at a maximum deep of 2 meters during a maximum time of 2 hours, contacts with alkaline acids at a pH between 4 and 13, contacts with solvents, severe vibrations having a maximum acceleration of 14.7 g, a frequency of 40 Hz in three directions for a maximum time of 3 hours, impacts at an acceleration of 6 g for 40 times minimum, a tension of 120 kg minimum and be flexed at 60 kg×cm.